Obesity is the second leading cause of preventable deaths in the United States and is associated with a wide range of diseases. In people who are obese, weight loss improves blood pressure, dyslipidemia, glycemia, and arthritis symptoms; reduces medication use for several disease processes; increases physical functioning; and enhances health-related quality of life. Despite these benefits, most patients who achieve weight loss regain much of this weight within a year, and few effective behavioral weight maintenance interventions have been identified. Thus, there is a dire need for effective interventions that can promote weight loss maintenance. Theoretical and empirical studies indicate that behavior maintenance is a distinct state that involves different psychological processes and behavioral skills than initial behavior change. The few trials that have tested weight loss maintenance interventions have not taken this distinction into account, which may partially explain their modest findings. The current study will evaluate a theoretically informed maintenance intervention. If effective, this intervention could reduce the need for future clinic visits to treat obesity and its many associated illnesses and could serve as a model for redesigning the MOVE! program. This 3.5-year study involves a two-arm randomized, controlled trial. During the run-in phase, 330 veterans aged d 75 with BMI e30 kg/m2 will participate in a 4-month, intensive, group-based weight loss program. Participants who lose at least 4 kg by the end of 4 months (n~230) will be randomized to receive (a) usual care (n~115) for 14 months or (b) a theoretically-informed maintenance intervention (n~115) for 10 months, followed by 4 months of no intervention contact to examine sustainability. The maintenance intervention will involve in-person group visits that transition to individualized telephone calls, and the frequency of contact with the interventionist will gradually taper over time. Outcomes will be assessed at the time of randomization and at 3, 6, 10, and 14 months post-randomization. Our hypotheses are that the maintenance intervention will result in at least 3.5 kg greater weight loss and greater improvements in caloric intake and physical activity over the study period, and that it will be cost-effective, compared to usual care.